Daily use of bar code scanners often encounter some professional technical terms, such as maximum resolution maximum resolution, optical resolution optical resolution, color resolution color depth, scanning methods, interface methods, etc., Yu Hengda To share the basic knowledge of the bar code scanner, the purpose is to help companies better use the bar code scanner.
In general, all types of bar code scanners have marked their optical resolution and maximum resolution. The unit of resolution is dpi, dpi is the abbreviation for English Dot Per Inch, which means the number of pixels per inch. After understanding the meaning of the resolution, let us take a look at how important the parameters of these scanners are to us.
1. The optical resolution refers to the actual amount of information that can be collected by the optical system of the barcode scanner, that is, the resolution of the scanner photosensitive element. For example, a scanner with a maximum scanning range of 216mm x 297mm (for A4 paper) can scan a maximum width of 8.5 inches (216mm). Its photosensitive original contains 5100 units and its optical resolution is 5100 points ÷ 8.5 inches = 600dpi . Common optical resolutions are 300 x 600 dpi, 600 x 1200 dpi, 1200 x 2400 dpi or higher.
2. Color resolution is also called color depth, color mode, color bit, or color gamma. All in all, it is an indicator that the bar code scanner can distinguish the fineness of color or gray scale. Its unit is bit (bit). The exact meaning of a color bit is how many "bits" are used to represent a pixel that is scanned. For example, 1 bit can only represent black and white pixels, because the numbers in the computer use binary, 1 bit can only represent two values (2 1 = 2) that is 0 and 1, they represent black and white, 8 bit can represent 256 gray levels (2 8 = 256), they represent different gray levels from black to white, 24bit can represent 16777216 colors (2 24 = 16777216), generally said that more than 24bit color is true color, of course, using 30bit, 36bit, 42bit model. In theory, the more colors, the more realistic the colors.
Let's analyze the relationship between resolution and file size. The general scanning application software can automatically calculate the file size when you preview the original manuscript, but knowing the file size calculation method helps you to make appropriate choices when managing the scanned file and determining the scanning resolution. The calculation formula of the black and white image file is: horizontal size × vertical size × (scanning resolution) 2 ÷ 8, the calculation formula of the color image file is: horizontal size × vertical size × (scanning resolution) 2 × color depth × 1/8 . For example, using a 24-bit color RGB method to scan an ordinary color photo (3.5 x 5 inches), scanning resolution is 300dpi, then the resulting image file length is 5 × 3.5 × 300 2 × 24 × 1/8 = 4725000 Byte 4.7MB .
OCR is the abbreviation of English Optical Character recognition, its function is to read the text image information on the printed matter through optical input devices such as bar code scanners, pattern recognition algorithm, and analyze the morphological characteristics of text to distinguish different Chinese characters. Chinese OCR is generally only suitable for identifying printed Chinese characters. The use of barcode scanners and OCR can partially replace the function of the keyboard to input Chinese characters, which is a labor-saving and quick text input method. Common OCR Tsinghua Wentong, Shangshu and so on.
